feat: Add AI tool building capabilities (#7336)

Github issue / Community forum post (link here to close automatically):
https://community.n8n.io/t/langchain-memory-chat/23733

---------

Signed-off-by: Oleg Ivaniv <me@olegivaniv.com>
Co-authored-by: Oleg Ivaniv <me@olegivaniv.com>
Co-authored-by: Val <68596159+valya@users.noreply.github.com>
Co-authored-by: Alex Grozav <alex@grozav.com>
Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>
Co-authored-by: Deborah <deborah@starfallprojects.co.uk>
Co-authored-by: Jesper Bylund <mail@jesperbylund.com>
Co-authored-by: Jon <jonathan.bennetts@gmail.com>
Co-authored-by: Michael Kret <88898367+michael-radency@users.noreply.github.com>
Co-authored-by: Giulio Andreini <andreini@netseven.it>
Co-authored-by: Mason Geloso <Mason.geloso@gmail.com>
Co-authored-by: Mason Geloso <hone@Masons-Mac-mini.local>
Co-authored-by: Mutasem Aldmour <mutasem@n8n.io>

packages/@n8n/chat/src/__tests__/utils/fetch.ts

@@ -0,0 +1,18 @@
+import type { LoadPreviousSessionResponse, SendMessageResponse } from '@/types';
+
+export function createFetchResponse<T>(data: T) {
+	return async () =>
+		({
+			json: async () => new Promise<T>((resolve) => resolve(data)),
+		}) as Response;
+}
+
+export const createGetLatestMessagesResponse = (
+	data: LoadPreviousSessionResponse['data'] = [],
+): LoadPreviousSessionResponse => ({ data });
+
+export const createSendMessageResponse = (
+	output: SendMessageResponse['output'],
+): SendMessageResponse => ({
+	output,
+});